Process of obtaining a double salt from a single salt



inventionii elates, tola method of res-I Patented FeBLZ B, 1933 r v comrm or was'mma; cAnn on-mma scares-Arron ,man

*raocassjor oisrammo A nouBLEsat'r-raoI-a siuetasapr Appliea tlon filed May 26,

covering double salts from,v single salts and particularly: torecovering sodium carbonate sulphatea a doublejsalt, containing; approx i 'mately onemolecule ofsodium carbonate and two molecules of sodium sulphate, from gsodium chloride, a o sing le salt.

- ,eThe double salt, sodium carbonate sulphate,

has the general formula--;of Na ;(CO .'S O}) and,apparently, a more exact chemical formu a .N 2C03- N 2S0'- Y sv far a k ow this double salt was firstdescribed in my Pat,-

enauei-slz aadaisd May 23, 1922, and filed June 30, 1919. With theaboveformula it? would contain about 27.2% sodium carbonate and 72.8% sodium sulphate, but I have found that-its compositionappears to vary slightly.

I have found-that double salts crystalize as veryfinecrystals upon agitationgduring rap id crystallization, while} single salts, under the same crystallizing conditions, tend to form crystalsirelatively much; coarser. taking advantage of this fact Iain enabl to separate successfully double salts fromf single salts whena doublesalt and a single salt crystallize so that: a mixture of the crystals results.

This characteristic of double salts I attribute' at this time to-theircomplicated molecular structure;

The vprocess is op as fine crystalscomparedto-the single salt thatmaybe crystalliz'ing from the solution at or about thesame time. The single salt from which ,the separation is: to 5, be ;made should, preferably be quite Jsoluble for when it- 1s insoluble or only-slightly soluble, there is ac-" cordinglyonly a little of it in solution and, correspondingly, very little of the salt to crystallizeg -l Under this, condition; where there is only a little" single salt,,the crystals of the single salt are usually fine andhence cannot be readily separated mechanically from the fine double salt crystals. a

Anobject ofmy inventionistoprovidean economical process ,gflof obtaining complex saltsqinj 'a substantially purestatey further object of myinvention is to pro also ,applicable to a solution from which atriple ,salt and :a single salt I crystallize substantially together. j The, com-, ,plicated triple saltshave a tendency to devel-r' 1930; "Serial n, 455,975;-

vide a rocess fiori 'obtaining ,sq'aitm carbonate. sulphate substantially freej from sodium chloride. n

The inventions possefi other advantage o'us features,some of which with the *foregoingwill be set forth in the followingdescrip -tionwhereIshalloutline in full one for'mof my processlbut it Zis understood that other forms may be iusediwithout deviatingi romy the essence of the invention ,1 shall preferably describet e process or my invention. as fapplied'to the recovery of j sodium carbonatesulphate from sodium chloride in Searles Lake brine-infCalifornia but,

it is understood that the process is applicable toother salts, to brines from' other sources, artificial solutions ofdouble and single saltsor solutions which give rise to such salts.

refer :to use,articial-evaporationand aiti cial. te p r tu stbu ural; e po as tion and natural/temperaturescan also be 7 used providihg the crystallization can take place v under the condition? of rapid crystal-- 7 rlization zand agitation; v V .1

In a modified formfof myaprocess of ob- 1 ft'aining sodium carbonate sulphate, described inmy Patent No. 1,417,139, Searles Lake brine was slowly; evaporated in summer to obtain, sodium carbonate sulphate mixed with sodiumchloride; I s.

1 Ihave found, however,that rapid evaporation of SearlesLake brine with agita- .tion, sodium carbonate sulphate can;- be ob,-

; tained' in a condition whereby it canbe more ,easilyseparated from sodium chloride. .By, rapidly evaporating thebrine'withina few hours time and agitatingsubstantially continuously, ;I am able" to produce; very fine crystals of sodiumrcarbonate sulphate and relatively coarsecrystals'of .sodium 'chloride,

without having the crystals stuck together, which would otherwise occur when evaporate ing in a solar pond in summer; The temperature of evaporation must be over 20 C. and

preferably over ,0. to .form this double salt.

. Evaporation can ebelcarried out quickly by means of 'the application; ofv artificial heat, It can also be accomplished quickly by natural evaporation whenplaced in veryshalr low vats at a depth of about 1 inch and ex-j posed to the heat of the suns rays during the daytime between April and October. In the latter case, at Searles Lake, the desired amount of evaporation can be accomplished in a few hours under usual weather conditions during the daytime and the temperature maintained above C.

By the terms rapidly evaporating? and. rapidly crystallizing I intend "to express the thought that these steps are accompllshed in a relatively short period of time compared j,

to the periods utilized heretofore. Thus in my Patent 1,417,139 I described theevaporationand crystallization being extended over a summer; *This is withoutmy "contemplaas compared to months, as stated in" 20 o ring.

tion here where I refer the evaporation and concentration be e (acted in a matter of hours,

i y Patents"1,417,139and 1,476,873. j Agitation is efi'ected in" artificial evapora tionfas bythe boiling of the solution, or by suitable mechanical. stirrers. With natural evaporation in the shallow onelinch. vat, agi tation is accomplished *by mechanical stir- The crystals ofsodiumlcarbonatesulphate produced in this-manner are very fine and tend to be held in suspensioninthe"brine while the crystals of sodium chloride are coarse and tend to settle out of the brine quickly. Hence thecrystals of sodium carbonate sulphate and sodium chloride can then be separated by settling the sodium chloride and decanting thesolution'containing the fine sodium carbonate sulphate crystals in suspension; 'The crystals ofth'etwo' saltscan also'be separated continuously by meansof a classifier or any'other well knownmeans of effecting mechanical separation. A 'device fwhichI term 'a hydroseparator is one form of convenient mechanical classifier, wherein the brine with the suspended crystals is flowed into a container while the velocityof flow of the brine with the suspended crystals is regulated so that thecoarse crystals settle quickly in the container, and the fine crystals are carried away with the fluid or brine stream into another 'containerwhere they are brine and agitating the recovered. This'is just'one form of classifier but other forms may beused totake advan-v the crystals, or the difi'erence in their size.

sodium carbonate sulphate and sodium chloride, and subjecting the crystallized sodium carbonate'sulphate and sodium chloride, to fluid action whereb sodium chloride crystals settle out ofthe fluid and the sodium carbonate sulphate crystalsare carried away by the fluid stream, and recovering the sodium carbonate sulphate.

A V 3. The process of obtaining sodium carbonate sulphate from Searles Lake brine which comprises rapidly evaporating the brine and agitating thebrine to crystallize sodium carbonate sulphate and sodium chlorideyand flowing the brine andsuspended crystals to separate rapidly settling sodium chloride crystals fromsloW settling sodium carbonate sulphate'crystals.

The process of obtaining sodium car; bonate sulphate 1 from Searles Lake brine .which comprises rapidly evaporating the brine and agitating thebrine to crystallize sodium carbonate sulphate'and sodium chlorideseparately in a'st'ate-of mechanical suspension in the brineyreducing the amount of agitation sutficien'tly toallow thesodium chloride tosettle, removing the brine and the suspended sodium carbonate sulphate, and recovering the suspended sodium carbonate sulphate.

' 5.- The process of obtaining sodium carbonate sulphate from a concentrated solution containing sodium, carbonate, sulphate and chloride ions, which comprises rapidly evaporatingand agitatin the solution above approximately-30 C. to epositsodium chloride and sodium"carbonate-sulphate, and

mechanically separating the crystals of sodium carbonate "sulphate from the crystals of sodium chloride. 1 V fipTheprocess of obtaining sodium carbonate sulphate from a solution containing the same; and another salt comprising evaporating the solution rapidly with agitation tocrystallize sodium carbonate sulphate and the other salt, and gmechanicallyseparatingthecrystals of sodium carbonate sulphate fromth e other salt.

'7. The recess of obtainingthe salts,

sodium car onatesulphate and sodium chlo- -l1de,'IfI'0I[l an a ueous' solution containing the same and'so ium chloride, which consists in agitating the brine while crystallizing these salts to create fine crystals of sodium carbonate sulphate and coarse crystals of sodiumfchloride, and mechanically separating the fine sodium carbonate sulphate crystals from the coarse sodium chloride crystals;

' 8." The roce'ss ot obtaining the salts,

sodium car onate sulphate and sodiumchloride, from an aqueous solution containing the same and sodiumfchloride, which consists in agitating the brine while, crystallizing these salts to create fine crystals ofsodiu'm carbonate sulphate and coarse crystals of sodium chloride, and flowing the hrine and suspended crystals toclassify the crystals acbonate sulphate from a solution containing,

' cording to size whereby the sodium-carbonate v sulphate is recovered isubstantially lseparate I fromthe sodium Chloride.

9. The process of obtaining sodium carthe same and a, another salt that will form crystals relatively larger than sodium carhonate sulphate upon evaporation and agita- I tion, which comprises evaporating and agitating the. solution; to crystallize the two salts, -and mechanically'se mating the fine sodium carbonatesulphate tom the coarse crystals] 15 a of the. other salt.

10. The" process of crystalizingithe salts fromsolution to produce fine crystals, ofsodium carbonate sul- I phate and coarse crystalsgof the othersalt, and mechanically separating the fine crystals from the coarse crystals. 11. That step in the process ate sulphate in substantially a pure state;

In testimony whereof, 'I have hereunto set GEQRGEQB;

my hand.

; 'obtainingjsodium cara 'bonatesulphate from-aisolution containing the-same and another 'salti that will 'form, I crystals relatively larger than sodiumcar-- bonate sulphate upon rapid crystallization from' solution which comprises rapidly g of recovering sodium carbonate sulphate separate from other salts which comprises rapidly eva 0- T "rating with agitation to crystallize (i ne' crystalsofsodium carbonatesulphate, and mechanically recovering the sodium carbon: 

